Lojban grammar

The grammar of Lojban is based on predicate logic. The majority of the grammar is borrowed from the prior "logical language" Loglan, and some of its features come from Láadan. The characteristic regularity, unambiguity, and versatility of Lojban grammar owes much to modern linguistics and computer programming—resources that were unavailable to the designers of earlier languages. Lojbanist Bob LeChevalier summarized one advantage of Lojban grammar as follows: "Lojban moves beyond the restrictions of European grammar. It overtly incorporates linguistic universals, building in what is needed to support the expressivity of the whole variety of natural languages, including non-European ones."

Formal grammars

Lojban texts can be parsed just as texts in programming languages are by using formal grammars such as PEG, YACC, Backus–Naur form. There are several parsers available.

Phonology

Lojban has 6 vowels and 21 consonants. The phonemes are commensurate with graphemes, which means Lojban has 27 letters each corresponding to a unique phoneme. Lojbanic graphemes can vary in mode; this article employs the Latin alphabet version, which is currently in the most common usage. The phonemes, on the other hand, are defined solely according to the International Phonetic Alphabet.
The tables below show typical realizations of sounds and the Latin alphabets in Lojban. In all cases except the rhotic consonant the first phoneme represents the preferred pronunciation, while the rest are the permitted variants intended to cover dissimilitude in pronunciation by speakers of different linguistic backgrounds.

Basic sounds

Note that simple vowel graphemes are never diphthongized like in English. Diphthongs are always written with two vowel graphemes.

Diphthongs

Lojban has 16 diphthongs, vowels that change quality during their emission but always being single syllable nuclei like pure vowels. Unlike English and similarly to languages such as Spanish, diphthongs are not distinct phonemes by themselves but are analyzed as a combination of "semi-vowel + vowel".
The combinations , , and , for instance, are all realized as the corresponding falling diphthongs. Triphthongs exist as combinations of a rising and a falling diphthong, e.g. .

Allophones

The vowels can be either rounded or unrounded. The consonants can be either aspirated or unaspirated, although the voiceless stops, and are usually aspirated to some degree. In general, consonants are not palatalized. The affricates /d͡ʒ/, /t͡ʃ/, /d͡z/, and /t͡s/ occur in Lojban, but they are not distinct phonemes, contrary to English /d͡ʒ/ and /t͡ʃ/. Each is considered to be a combination of an appropriate stop and fricative phoneme: the sequences , , and , respectively. The rhotic sounds are all equally acceptable as an identical phoneme.,,, and may be syllabic.

Buffering of consonant clusters

For those who, given their native language background, may have trouble pronouncing consonant clusters, there is the option of inserting buffer vowels between them, as long as they differ sufficiently from the phonological vowels and are pronounced as short as possible. This mechanism can be described as a form of anaptyxis. Possible choices include ,, and . The resulting added syllables are completely ignored by the grammar, including for the purposes of stress determination.

Orthography

Lojban may be written in different orthography systems as long as it meets the required regularities and unambiguities. Some of the reasons for such elasticity would be as follows:

Lojban is rather defined by the phonemes, therefore, as long as they are correctly rendered so as to maintain the Lojbanic audio-visual isomorphism, a representational system can be said to be an appropriate orthography of the language;
Lojban is meant to be as culturally neutral as possible, so it is never crucial or fundamental to claim that some particular orthography of some particular languages should be the dominant mode.

Lojbanist Kena extends this principle to argue that even an [|original orthography of the language] is to be sought.

Latin/Roman mode

Lojban's Latin alphabet consists of 23 lerfu a b c d e f g i j k l m n o p r s t u v x y z plus 3 semi-lerfu ',. which are used. They are intentionally ordered in accordance with that of ASCII characters.
Capitalization may be applied to mark a non-standard stressed syllable as in cmevla, but they are not considered separate lerfu. Whether a single vowel or the entire syllable is capitalized is a matter of preference; for example, the name "Josephine" can be rendered as either DJOzefin. or djOzefin..
Punctuation marks are not mandatory; such notions as question or exclamation are expressed with words rather than unpronounced symbols.

Cyrillic mode

This mode was conceived when the introductory Lojban brochure was translated into Russian. 23 lerfu а б в г д е ж з и к л м н о п р с т у ф х ш ъ plus 3 semi-lerfu ',. are used. The hard sign ъ is assigned to the open-mid vowel. Diphthongs are written as vowel pairs, as in the Roman mode.

Tengwar mode

Kena argues for writing Lojban using Tengwar, arguing that:

the Latin alphabet is too strongly related to Western civilizations, and thus probably introduces some kind of cultural bias in Lojban. Lojban wants to be both logical and culturally neutral, the Tengwar already are;
the Tengwar system inherently contains some main Lojban morphology rules, making Lojban easier to learn when it is written with Tengwar.

Advocates of this mode include Eric S. Raymond.

Zbalermorna mode

Another option for cultural neutrality is zbalermorna, an abugida created by la kmir. It is designed with handwriting in mind. The word zbalermorna is a combination of zbasu, lerfu, and morna.
Much like in the Shavian alphabet, the voiced consonant is written with a rotated version of the glyph used to write the voiceless consonant. Common design elements are used for different types of consonants, i.e. plosives, both sibilant and non-sibilant fricatives, liquids, and nasals. Since x doesn't have a voiced or voiceless counterpart, it is written with a circle.
Vowels are written as diacritics applied to consonants. Semivowels i and u use their own separate consonant glyphs, while the other allowed diphthongs, au, ai, ei, and oi, use their own diacritics. This script also has a separate system for vowels and the aforementioned diphthongs for use in names and foreign words to make them stand out. Because diphthongs get their own letters, this system also removes the need for a slaka bu.
The .y'y and denpa bu are written with the same symbols as the Latin script. The pattern of.C'C can be written with the two symbols merged, allowing attitudinals to be written more naturally.
The design also allows .i, the most common cmavo in Lojban, to be written with just two dots, akin to a colon.

Japanese mode

A Japanese hiragana version of Lojban orthography has been proposed, in which case more than 80 lerfu may be used. This mode is not without certain technical issues since the hiragana are always syllabic, indicating an open syllable, requiring some special attention when representing the Lojbanic consonant clusters. Several example haiku compositions in the orthography have been created.

Morphology

Lojban has 3 word-classes: brivla, cmavo, and cmevla. Each of them has uniquely identifying morphological properties, so that one can unambiguously recognize which word is of which part of speech in a string of the language. They may be further divided in sub-classes.
There also exist affixes assigned to some of the brivla and cmavo.

brivla – verbs

brivla carry the content of an expression. The bare brivla corresponds to the verb in English. Additional words can be used to transform it into what corresponds to English common nouns, adjectives, or adverbs. Brivla may be identified by the following morphological properties:

Have more than one syllable
Are penultimately stressed
Have a consonant cluster in the first 5 lerfu including the second consonant
Start with a consonant
End with a vowel

A word such as lobypei will still be considered as a brivla because the special gluing vowel y between b and p is to be ignored and therefore a consonant cluster assumes its existence within it.
Unlike verbs in English, brivla do not inflect for tense, person, or number.
Brivla's sub-classes are as follows, with some examples.

gismu – core verbs

The brivla which constitute the lexical core of the language are called gismu. They are invariably five-letter words, which distinguishes it from the other types of brivla, and are in a form of either CVCCV or CCVCV. Being two syllables means that the general rule of brivla to be stressed penultimately will always cause the first syllable of a gismu to be stressed.

They have been chosen or added as root words because they

represent concepts that are very familiar and basic,
represent concepts the usage of which is equally frequent among different languages,
would be helpful in constructing more complex words, or
represent fundamental grammatical concepts of Lojban.

The main source languages from which they were drawn are Arabic, Chinese, English, Hindi, Russian, and Spanish. Here is further explanation of the nature of gismu by Cowan:
According to Robin Turner, the creation was algorithmically done by computer.
Approximately 1350 gismu exist, which is a relatively small number when compared to that of English words ranging from 450,000 up to 1,000,000. Theoretically, by learning only these root words, as well as their fragmental forms and some major structure words, one will be able to communicate effectively in Lojban.